Display device

ABSTRACT

According to one embodiment, a display device includes a pair of substrates including a display area in which pixels are arranged, pixel electrodes and memories provided in the pixels, signal lines supplied with digital signals, switching elements connecting the memories and the signal lines, scanning lines supplied with scanning signals, a first driver unit, and a second driver unit. The first driver unit is provided in a peripheral area around the display area, and supplies the digital signal to the signal line. The second driver unit is provided in the peripheral area, and supplies the scanning signal to the scanning line. In the display device, at least a part of the first driver unit is provided between the display area and the second driver unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/656,008 filed Oct. 17, 2019, which is a continuation of U.S.application Ser. No. 16/268,091, filed Feb. 5, 2019, which is acontinuation of U.S. application Ser. No. 15/417,703 filed Jan. 27, 2017and is based upon and claims the benefit of priority from JapanesePatent Application No. 2016-016115, filed Jan. 29, 2016, the entirecontents of each of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a display device.

BACKGROUND

Display devices such as liquid crystal display devices in which a memoryis provided for each pixel in a display area are known. This type ofdisplay device writes a digital signal to each memory in accordance withthe image to be displayed, and sets the drive potential of each pixel topotential corresponding to the digital signal stored in the memory. Inthis way, the display device displays the image in the display area. Thesystem for driving the pixels based on the digital signals stored in thememories in the above manner is called a digital mode or a digitaldriving system.

The display device is required to minimize the peripheral area aroundthe display area (in other words, to minimize the width of the frame).In the display device in digital mode, various lines and circuits needto be provided in the peripheral area to control the memories. Thus, thecircuit layout of the peripheral area must be designed in some way toreduce the width of the frame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of the overall structure of a display deviceaccording to one embodiment.

FIG. 2 shows an example of the circuit structure of the display device.

FIG. 3 shows an example of the equivalent circuit of a subpixel providedin the display device.

FIG. 4 is a timing chart showing an example of an operation in a storageperiod in the display device.

FIG. 5 is a timing chart showing an example of an operation in a displayperiod in the display device.

FIG. 6 shows the general structure of a first circuit unit provided inthe display device.

FIG. 7 shows the general structure of a second circuit unit provided inthe display device.

FIG. 8 shows an example of a circuit layout applicable to first andsecond driver units provided in the display device in a first areaincluded in a peripheral area.

FIG. 9 shows another example of a circuit layout applicable to the firstand second driver units in the first area.

FIG. 10 shows an example of a circuit layout applicable to the seconddriver unit in a second area included in the peripheral area.

FIG. 11 shows a specific example of a circuit layout applicable to thefirst area.

FIG. 12 is an enlarged view of the first circuit unit of FIG. 11.

FIG. 13 is an enlarged view of the second circuit unit of FIG. 11.

DETAILED DESCRIPTION

In general, according to one embodiment, a display device comprises apair of substrates, an optical element layer, pixel electrodes,memories, signal lines, switching elements, scanning lines, a firstdriver unit and a second driver unit. The pair of substrates comprises adisplay area in which a plurality of pixels are arranged. The opticalelement layer is provided between the pair of substrates. The pixelelectrodes and the memories are provided in the respective pixels. Thesignal lines are supplied with digital signals to be stored in thememories. The switching elements connect the memories and the signallines. The scanning lines are supplied with scanning signals forcontrolling the switching element. The first driver unit is provided ina peripheral area around the display area, and is configured to supplythe digital signals to the signal lines. The second driver unit isprovided in the peripheral area, and is configured to supply thescanning signals to the scanning lines. In the display deice, at least apart of the first driver unit is provided between the display area andthe second driver unit.

One embodiment will be described hereinafter with reference to theaccompanying drawings.

The disclosure is merely an example, and proper changes in keeping withthe spirit of the invention, which are easily conceivable by a person ofordinary skill in the art, come within the scope of the invention as amatter of course. In addition, in some cases, in order to make thedescription clearer, the drawings show schematic illustration ratherthan as an accurate representation of what is implemented. However, suchschematic illustration is merely exemplary, and in no way restricts theinterpretation of the invention. In the drawings, reference numbers ofcontinuously arranged elements equivalent or similar to each other areomitted in some cases. Further, in the specification and drawings,structural elements which function in the same or a similar manner tothose described in connection with preceding drawings are denoted bylike reference numbers, detailed description thereof being omittedunless necessary.

In the present embodiment, as an example of a display device, a liquidcrystal display device having the function of the above digital mode isdisclosed. However, the present embodiment does not prevent applicationof individual technical ideas disclosed in the embodiment to other typesof display devices. Other types of display devices are assumed to be,for example, a self-luminous display device such as an organicelectroluminescent display (OELD) device, or an electronic paper displaydevice having a cataphoresis element.

This specification explains the basic structure and operation of adisplay device with reference to FIG. 1 to FIG. 5.

FIG. 1 is a plan view showing an example of the overall structure of adisplay device 1. The display device 1 comprises a first substrate SUB1and a second substrate SUB2. The first substrate SUB1 is attached to thesecond substrate SUB2 such that they face each other. A liquid crystallayer (specifically, the liquid crystal layer LC described later) issealed between the first substrate SUB1 and the second substrate SUB2.The liquid crystal layer is an example of an optical element layer. Asother optical element layers, the above organic electroluminescentelement, the above cataphoresis element and a microelectromechanicalsystems (HEMS) shutter element are considered.

The display device 1 comprises a display area DA, and a peripheral areaSA surrounding the display area DA. In the overlapping area of the firstand second substrates SUB1 and SUB2, the display area DA is equivalentto an area in which an image is displayed. Pixels PX are provided in thedisplay area DA. Specifically, a large number of pixels PX are arrangedin matrix in a first direction X and a second direction Y in the displayarea DA. The first direction X is, for example, perpendicular to thesecond direction Y. In the overlapping area of the first and secondsubstrates SUB1 and SUB2, the peripheral area SA is equivalent to anarea outside the display area DA.

In the example of FIG. 1, the display area DA is precisely circular.However, the display area DA may have other shapes, such as an ovalshape, a polygonal shape, or a shape including a curve at least in apart of the outline. In the example of FIG. 1, the first substrate SUB1,the second substrate SUB2 and the peripheral area SA are also preciselycircular. However, the first substrate SUB1, the second substrate SUB2and the peripheral area SA may nave other shapes in a manner similar tothat of the display area DA.

The display device 1 further comprises a control device 2, a firstdriver unit 3 and a second driver unit 4. The control device 2 is, forexample, an integrated circuit mounted on the first substrate SUB1, andfunctions as a signal supply portion which outputs various signalsnecessary for displaying an image based on the image data input fromoutside. The control device 2 may not be mounted on the first or secondsubstrate SUB1 or SUB2, and may be connected to the first and secondsubstrates SUB1 and SUB2 via a flexible wiring board.

For example, the first driver unit 3 and the second driver unit 4 areformed on the first substrate SUB1 in the peripheral area SA. In theexample of FIG. 1, the first driver unit 3 has an arc-shape along themarginal portion of the lower part of the display area DA (in otherwords, along the marginal portion on the control device 2 side). Thesecond driver unit 4 has an arc-shape along the marginal portion of theleft part of the display area DA. The first driver unit 3 may be calleda horizontal driver, a signal line drive circuit, a source driver, etc.The second driver unit 4 may be called a vertical driver, a scanningline drive circuit, a gate driver, etc.

For example, the peripheral area SA is shielded against light by alight-shielding layer formed on the second substrate SUB2. Thelight-shielding layer can prevent light leak from the peripheral area SAand light reflection on the circuits or lines formed in the peripheralarea SA.

The first driver unit 3 comprises a plurality of first circuit units 30.The second driver unit 4 comprises a plurality of second circuit units40.

The peripheral area SA comprises a first area A1 and a second area A2.In the first area A1, a part of the first driver unit 3 (in other words,at least one of the first circuit units 30) is located between thesecond driver unit 4 and the display area DA. In the second area A2, thefirst driver unit 3 is not located between the second driver unit 4 andthe display area DA. In other words, the first area A1 includes thesecond circuit units 40 and at least one of the first circuit units 30.The second area A2 includes the second circuit units 40 and does notinclude any first circuit unit 30.

FIG. 2 shows the general circuit structure of the display device 1. Tosimplify the figure, the display area DA is shown as a rectangular area,and the first and second driver units 3 and 4 are linearly shown. In thepresent embodiment, each pixel PX includes red (R), green (G) and blue(B) subpixels SP. In the following explanation, the red, green and bluesubpixels SP are called subpixels SPR, SPG and SPB, respectively. In thepresent disclosure, each subpixel SP may be simply referred to as apixel in some cases.

In the example of FIG. 2, subpixels SPR, SPG and SPB included in eachpixel PX are arranged in the first direction X. However, the layout ofthe pixels PX is not limited to the example of FIG. 2. For example, eachpixel PX may further include a subpixel SP corresponding to anothercolor such as white (W). At least one or some of subpixels SP includedin each pixel PX may be arranged in the second direction Y. Each pixelPX may include a plurality of subpixels SP corresponding to the sanecolor.

The display device 1 comprises a plurality of signal lines S and aplurality of scanning lines GD. The signal lines S and the scanninglines GD are formed in the first substrate SUB1. The signal lines S areconnected to respective first circuit units 30. The scanning lines GDare connected to respective second circuit units 40. The signal lines Sextend in the display area DA in the second direction Y, and arearranged in the first direction X. The scanning lines GD extend in thedisplay area DA in the first direction X, and are arranged in the seconddirection Y.

Each subpixel SP comprises a memory 10 and a pixel electrode PE in thefirst substrate SUB1. The memory 10 stores a digital signal supplied viathe signal line S. The pixel electrode PE faces a common electrode CEformed in the second substrate SUB2. The common electrode CE may beformed in the first substrate SUB1. The pixel electrode PE and thecommon electrode CE may be formed of a transparent conductive materialsuch as indium tin oxide (ITO). The common electrode CE is formed over aplurality of subpixels SP, and is connected to an AC drive circuit 20provided in the control device 2 via a common electrode line LCM.

The display device 1 comprises a color filter facing a correspondingsubpixel SP. The colors of the color filters correspond to the displaycolors of their respective opposite subpixels SP. The color filters areformed in, for example, the second substrate SUB2.

The display device 1 may be, for example, a reflective type displaydevice. In this case, a reflective layer for reflecting outside light isformed in the display area DA. An image is displayed using the lightreflected on the reflective layer. A front light may be provided on theexternal side of the second substrate SUB2 such that an image isdisplayed using the light emitted from the front light.

The display device 1 may be a transmissive type display device. In thiscase, a backlight is provided on the rear side of the first substrateSUB1 such that an image is displayed using the light emitted from thebacklight. The display device 1 may have both the reflective functionand the transmissive function.

FIG. 3 shows an example of the equivalent circuit of each subpixel SP.Each subpixel SP comprises the above pixel electrode PE, the abovememory 10, a select control circuit 11, and a storage control circuit12.

The select control circuit 11 comprises a switching element Q1 whoseinput terminal is connected to a first drive line DL1, and a switchingelement Q2 whose input terminal is connected to a second drive line DL2.For example, a first drive signal xFRP which is the display signal of animage is supplied from the control device 2 to the first drive line DL1.A second drive signal FRP which is the non-display signal of an image issupplied from the AC drive circuit 20 to the second drive line DL2.

The select control circuit 11 further comprises a select signal line 12a connecting the output terminals of switching elements Q1 and Q2 andthe pixel electrode PE.

In FIG. 3, the line extending from the AC drive circuit 20 branches offto the second drive line DL2 and the common electrode line LCM. Thus, inthis example, signals FRP and VCOM have the same potential.

The memory 10 comprises switching elements Q3 to Q6. A first power lineLP1 is connected to the input terminals of switching elements Q3 and Q5.Power source voltage VRAM is applied to the first power line LP1 fromthe second circuit unit 40. A second power line LP2 to which voltage VSSis applied is connected to the input terminals of switching elements Q4and Q6. The output terminals of switching elements Q3 and Q4 areconnected to the control terminal of switching element Q2 to structure afirst inverter. The output terminals of switching elements Q5 and Q6 areconnected to the control terminal of switching element Q1 to structure asecond inverter. These inverters are parallely connected in oppositedirections, and selectively turn on one of switching elements Q1 and Q2.

The first circuit unit 30 supplies a digital signal SIG to the signalline S. The storage control circuit 12 is a circuit for storing adigital signal SIG supplied to the signal line S in the memory 10, andcomprises a switching element Q7. The input terminal of switchingelement Q7 is connected to the signal line S. The output terminal ofswitching element Q7 is connected to the control terminals of switchingelements Q3 and Q4. The scanning line GD is connected to the controlterminal of switching element Q7. A scanning signal GATED is suppliedfrom the second circuit unit 40 to the scanning line GD.

All of switching elements Q1 to Q7 are, for example, thin-filmtransistors, and are formed in the first substrate SUB1. The first driveline DL1, the second drive line DL2, the first power line LP1, thesecond power line LP2 and the scanning line GD are also formed in thefirst substrate SUB1, and are connected to the subpixels SP arranged inthe first direction X.

The display device 1 having the above structure is allowed to drive eachsubpixel SP in digital mode. The digital mode is a system forcontrolling the luminance of each subpixel SP in monochrome by simplyapplying on and off based on the digital signal stored in the memory 10.In the following explanation, it is assumed that the display device 1 isa display device in normally-black mode. It is assumed that, when thememory 10 is made high (high potential), the subpixel SP is on (whitedisplay). It is assumed that, when the memory 10 is made low (lowpotential), the subpixel SP is off (black display).

In digital mode, a storage period and a display period are repeated. Ina storage period, a digital signal SIG supplied to each signal line S isstored in the memories 10. In a display period, the first or seconddrive signal xFRP or FRP is selectively supplied to each pixel electrodePE in accordance with the digital signal (a high or low digital signal)stored in the memory 10.

In the following explanation, a group of subpixels SP arranged in thefirst direction X in the display area DA is called a horizontal line. Ina storage period, a scanning pulse is supplied to each scanning line GDin series. The digital signal SIG of a horizontal line corresponding toeach scanning line GD supplied with the scanning pulse is supplied toeach signal line S in series. In this way, the digital signal SIG iswritten to each memory 10 in series in accordance with image data basedon each horizontal line.

FIG. 4 is a timing chart showing an example of an operation in a storageperiod in the display device 1. This timing chart particularly looks atthe subpixel SP shown in FIG. 3 and shows the change in a digital signalSIG, the pixel potential PIX of the pixel electrode PE, a common signalVCOM, a scanning signal GATED, power source voltage VRAM and the memorypotential RAM stored in the memory 10.

In the following explanation, a period for writing a digital signal SIGto one horizontal line is defined as a horizontal period TH. In ahorizontal period TH, the digital signal SIG of the signal line S is setto the potential to be written to each memory 10. It is assumed thathigh voltage VDD corresponds to white display, and low voltage VSScorresponds to black display. The power source voltage VRAM of the firstpower line LP1 is decreased from VDD2 to VDD1. Subsequently, thescanning signal GATED of the scanning line GD is increased from VSS2 toVDD2. Thus, switching element Q7 is turned on, and the memory 10 isconnected to the signal line S. At this time, as shown by the arrow inthe figure, the level of the digital signal SIG supplied to the signalline S is written to the memory 10. FIG. 4 shows an example in which ahigh signal is written to the memory 10.

Subsequently, the scanning signal GATED is decreased to VSS2. Thus,switching element Q7 is turned off, and the power source voltage VRAM isincreased to VDD2 which is the voltage for turning switching elements Q1and Q2 on. At this time, the voltage of the memory 10 is also increasedfrom VDD1 to VDD2. In this way, the memory 10 connects the first powerline LP1 and switching element Q1, and turns switching element Q1 on bythe power source voltage VRAM. The memory 10 connects the second powerline LP2 and switching element Q2, and turns switching element Q2 off byvoltage VSS. Since switching element Q1 is turned on, the first drivesignal xFRP of the first drive line DL1 is supplied to the select signalline 12 a.

When the potential applied to the memory 10 is low so as to correspondto black display, the memory 10 connects the second power line LP2 andswitching element Q1, and turns switching element Q1 off by voltage VSS.The memory 10 connects the first power line LP1 and switching elementQ2, and turns switching element Q2 on by power source voltage VRAM.Since switching element Q2 is turned on, the second drive signal FRP ofthe second drive line DL2 is supplied to the select signal line 12 a.The memory 10 exclusively turns one of switching elements Q1 and Q2 onby the stored voltage, and selects one of the first and second drivelines DL1 and DL2 as the connection destination of the select signalline 12 a.

FIG. 5 is a timing chart showing an example of an operation in a displayperiod in the display device 1. This timing chart particularly looks atone subpixel SP in a manner similar to that of FIG. 4. In the examplesof FIG. 4 and FIG. 5, frame-inversion control is used. Inframe-inversion control, the polarity of potential between the pixelelectrode PE and the common electrode CE is periodically inverted basedon each frame period TF in all the subpixels SP arranged in the displayarea DA. A process for rewriting the memories 10 in each horizontal lineconstituting one frame is performed during, for example, one frameperiod TF. In other words, the series of horizontal periods TH shown inFIG. 4 is included in one frame period TF. In the horizontal periods THshown in FIG. 4, signal VCOM is constant. However, as shown in FIG. 5, adisplay period includes a plurality of frame periods TF. In the displayperiod, the potential of signals VCOM and FRP changes between VSS andVDD depending on each frame period TF. The first drive signal xFRP is anAC signal having a phase opposite to that of the second drive signalFRP, and changes between voltage VDD and voltage VSS depending on eachframe period TF.

In the display period, when switching element Q1 is turned on by thememory 10, the first drive line DL1 is connected to the pixel electrodePE. When switching element Q2 is turned on by the memory 10, the seconddrive line DL2 is connected to the pixel electrode PE. FIG. 5 shows anexample in which the pixel potential PIX is set to the first drivesignal xFRP since the first drive line DL1 is connected to the pixelelectrode PE. In this case, the difference in potential is generatedbetween the pixel electrode PE and the common electrode CE such thatwhite display is applied to the subpixel SP. When the second drive lineDL2 is connected to the pixel electrode PE, no difference in potentialis generated between the pixel electrode PE and the common electrode CEsuch that black display is applied to the subpixel SP.

By the above operation, white display or black display is applied toeach subpixel SP. In this way, an image is displayed in the display areaDA.

Now, this specification explains the first circuit units 30 and thesecond circuit units 40 with reference to FIG. 6 and FIG. 7.

FIG. 6 shows the general structure of the first circuit unit 30. Thefirst circuit unit 30 shown in FIG. 6 supplies a digital signal SIG totwo subpixels SPR1 and SPR2 corresponding to red, two subpixels SPG1 andSPG2 corresponding to green, and two subpixels SPB1 and SPB2corresponding to blue. For example, subpixels SPR1, SPG1 and SPB1 areincluded in one pixel PX. Subpixels SPR2, SPG2 and SPB2 are included ina pixel PX adjacent to the above pixel PX in the first direction X.

The first circuit unit 30 comprises a first shift register 31, a firstlatch circuit 32, a second latch circuit 33 and a first buffer circuit34. The first latch circuit 32 comprises memory elements MA1 to MA6. Thesecond latch circuit 33 comprises memory elements MB1 to MB6. The firstbuffer circuit 34 comprises buffer elements BA1 to BA6.

The first shift register 31 is connected to the first latch circuit 32via two first connective lines CL1. Memory elements MA1 to MA6 areconnected to memory elements MB1 to MB6 via respective second connectivelines CL2. Memory elements MB1 to MB6 are connected to buffer elementsBA1 to BA6 via respective third connective lines CL3. Buffer elementsBA1 to BA6 are connected to the signal lines S extending to subpixelsSPR1, SPG1, SPB1, SPR2, SPG2 and SPB2, respectively.

The first shift register 31, the first latch circuit 32, the secondlatch circuit 33 and the first buffer circuit 34 operate with voltagesVDD1 and VSS as the drive power supply. When a reset signal xRST isinput, the first shift register 31 clears outputs OUT and xOUT so as tobe off-potential. When clock HCK is input, the first shift register 31loads and latches the output data DI of the first shift register 31 ofthe first circuit unit 30 in the preceding stage (hereinafter, referredto as a preceding register). At this time, when the output data DI ofthe preceding register is high, output OUT of the first shift register31 is made high, and output xOUT is made low. When the output data ofthe preceding register is low, output OUT of the first shift register 31is made low, and output xOUT is made high.

Output OUT of the first shift register 31 is output to the first shiftregister 31 of the first circuit unit 30 in the next stage. Further,outputs OUT and xOUT of the first shift register 31 are supplied tomemory elements MA1 to MA6 as latch pulses.

In the example of FIG. 6, data buses DBL extend between the first shiftregister 31 and the first latch circuit 32. The data buses DBL mayextend between the first latch circuit 32 and the second latch circuit33. The data buses DBL include six lines supplied with video data itemsR1, G1, B1, R2, G2 and B2. Video data items R1, G1, B1, R2, G2 and B2are data items indicating a digital signal SIG supplied to subpixelsSPR1, SPG1, SPB1, SPR2, SPG2 and SPB2, respectively.

When high output data DI is input to the first shift register 31, forexample, video data items R1, G1, B1, R2, G2 and B2 supplied to the databuses DBL are latched by memory elements MA1 to MA6.

Timing pulses Ds and xDs are input to memory elements MB1 to MB6. Usingtiming pulses Ds and xDs, memory elements MB1 to MB6 latches the videodata items latched by memory elements MA1 to MA6 at the same time. Inthis way, the time when video data items are transmitted from the firstlatch circuit 32 to the second latch circuit 33 is the same in, forexample, all the first circuit units 30. Thus, the video data items ofsubpixels SP arranged in the first direction X (in a horizontal line)are provided in the second latch circuit 33 of each first circuit unit30.

Buffer elements BA1 to BA6 output a digital signal SIG corresponding tothe video data items latched by memory elements MB1 to MB6 to the signallines S. In this way, a digital signal SIG is concurrently supplied tothe signal lines S in accordance with the video data items latched bythe second latch circuit 33 of each first circuit unit 30. Thus, data iswritten to the memory 10 of each subpixel SP. While a digital signal SIGis supplied, video data items R1, G1, B1, R2, G2 and B2 in the nexthorizontal line are latched by the first latch circuit 32.

According to the above structure, the video data items of two pixels PXcan be processed by one first circuit unit 30. Thus, the drive frequencyof the first driver unit 3 can be reduced. In addition, the video dataitems in the next horizontal line can be latched by the first latchcircuit 32 while the video data items of the second latch circuit 33 aresupplied to the signal lines S. Thus, the processing efficiency can beimproved.

The first circuit unit 30 may include only one latch circuit. The firstcircuit unit 30 may supply a digital signal SIG to only the subpixels SPincluded in one pixel PX, or may supply a digital signal SIG to thesubpixels SP included in three or more pixels PX.

FIG. 7 shows the general structure of the second circuit unit 40. Thesecond circuit unit 40 comprises a second shift register 41, two secondbuffer circuits 42A and 42B, and a power supply circuit 43. The secondshift register 41, second buffer circuits 42A and 42B and the powersupply circuit 43 are connected to each other via fourth connectivelines CL4.

The second shift register 41 and second buffer circuits 42A and 42Boperate with voltages VDD2 and VSS as the drive power supply. The powersupply circuit 43 operates with voltages VDD1 and VDD2 as the drivepower supply. When a reset signal xRST is input, the second shiftregister 41 clears outputs OUT and xOUT so as to be, for example,off-potential. When clock VCK is input, the second shift register 41loads and latches the output data DI of the second shift register 41 ofthe second circuit unit 40 in the preceding stage (hereinafter, referredto as a preceding register). For example, when the output data DI of thepreceding register is high, output OUT of the second shift register 41is made high, and output xOUT is made low. When the output data DI ofthe preceding register is low, output OUT of the second shift register41 is made low, and output xOUT is made high.

Outputs OUT and xOUT of the second shift register 41 are supplied tosecond buffer circuits 42A and 42B, and are output to the second shiftregister 41 of the second circuit unit 40 in the next stage. Outputs OUTand xOUT are supplied to the power supply circuit 43. The power supplycircuit 43 sets the above power source voltage VRAM so as to be high orlow in accordance with the state of output OUT or xOUT.

Enable signal xENB1 is supplied to second buffer circuit 42A. Enablesignal xENB2 is supplied to second buffer circuit 42B. For example, whenoutputs OUT and xOUT are high and low, respectively, and further whenenable signal xENB1 is input, second buffer circuit 42A supplies a highscanning signal GATED to the scanning line GD connected to second buffercircuit 42A. For example, when outputs OUT and xOUT are high and low,respectively, and further when enable signal xENB2 is supplied, secondbuffer circuit 42B supplies a high scanning signal GATED to the scanningline GD connected to second buffer circuit 42B. In the subpixel SPconnected to each scanning line GD supplied with a high scanning signalGATED, switching element Q7 is turned on. In this way, in thesesubpixels SP, a digital signal SIG supplied to the signal lines S can bewritten to the memories 10.

In the second circuit unit 40 having the above structure, when thesecond shift register 41 in a stage latches the data for driving, twoscanning lines GD can be driven in order by enable signals xENB1 andxENB2. Thus, there is no need to prepare the second shift register 41for each scanning line GD. In this manner, the driving frequency of thesecond shift register 41 can be reduced.

In a common display device, the display area DA is a rectangle havingsides in the first direction X and sides in the second direction Y. Inthis case, normally, the first driver unit 3 is linearly provided in thefirst direction X, and the second driver unit 4 is linearly provided inthe second direction Y. Since each of the first and second driver units3 and 4 is provided along the display area DA, the first and seconddriver units 3 and 4 can be close to the display area DA over the entirelength.

In the circular display area DA as shown in FIG. 1, if the first andsecond driver units 3 and 4 are linearly provided, a useless space isdefined between the display area DA and the first or second driver unit3 or 4. In the present embodiment, the first and second driver units 3and 4 have an arc-shape along the display area DA as shown in FIG. 1.Further, in the first area A1, at least a part of the first driver unit3 is provided between the second driver unit 4 and the display area DA.This structure allows prevention of a useless space in the peripheralarea SA and reduction in the width of the frame.

However, in the first area A1, lines such as the scanning lines GDextending from the second driver unit 4 to the display area DA must passthrough the area of the first driver unit 3. When the first and seconddriver units 3 and 4 have an arc-shape, the lines in these driver unitsmust be bent where necessary. In consideration of this factor, thecircuit layout of the first and second driver units 3 and 4 needs to bedesigned such that the efficiency is improved.

FIG. 8 shows an example of a circuit layout applicable to the first andsecond driver units 3 and 4. FIG. 8 shows the general structures of theperipheral area SA and the display area DA near the first area A1.

The first driver unit 3 comprises the first circuit units 30 arranged inan arc-form along the display area DA. In FIG. 8, a single signal line Sis connected to a corresponding first circuit unit 30. However, moresignal lines S (for example, six signal lines S as shown in FIG. 6) maybe connected to a corresponding first circuit unit 30.

The second driver unit 4 comprises the second circuit units 40 arrangedin an arc-form along the first driver unit 3 and the display area DA. InFIG. 8, a single scanning line GD is connected to a corresponding secondcircuit unit 40. However, more scanning lines GD (for example, twoscanning lines GD as shown in FIG. 7) may be connected to acorresponding second circuit unit 40.

Each first circuit unit 30 is divided into two circuits. In thefollowing explanation, one of the two circuits is called horizontalcircuit H1, and the other one is called horizontal circuit H2. Forexample, at least one of the first shift register 31, the first latchcircuit 32, the second latch circuit 33 and the first buffer circuit 34shown in FIG. 6 is included in horizontal circuit H1. The other elementsare included in horizontal circuit H2. Alternatively, horizontalcircuits H1 and H2 may be defined by more-specific circuit elements. Forexample, horizontal circuit H1 may include memory elements MA1 to MA3,and horizontal circuit H2 may include memory elements MA4 to MA6. Eachfirst circuit unit 30 may be divided in an arbitrary way, and variousforms may be applied depending on the structure of the first circuitunits 30. Further, each first circuit unit 30 may be divided into threeor more horizontal circuits.

In the example of FIG. 8, horizontal circuits H1 and H2 are linearlyarranged in the second direction Y. Moreover, the scanning line GDextends in the first direction X between horizontal circuits H1 and H2.Horizontal circuits H1 and H2 are electrically connected to each othervia a connective line provided in a layer different from that of thescanning line GD.

If each first circuit unit 30 is not divided into a plurality ofhorizontal circuits, the scanning lines GD must be bent so as to avoidthe first circuit units 30. Thus, there is a need to define a spacearound the first circuit units 30 such that the scanning lines GD avoidthe first circuit units 30. In the example of FIG. 8, the scanning liensGD are allowed to extend to the display area DA without bending thefirst circuit unit 30. Thus, it is possible to minimize the space forthe scanning lines GD. In this way, the layout of the peripheral area SAis improved in terms of efficiency.

FIG. 9 shows another example of a circuit layout applicable to the firstand second driver units 3 and 4. In the example of FIG. 9, in additionto the first circuit units 30, each second circuit unit 40 is dividedinto two circuits. In the following explanation, one of the two circuitsis called vertical circuit V1, and the other one is called verticalcircuit V2. Vertical circuits V1 and V2 are electrically connected toeach other via one or more connective lines.

For example, at least one of the second shift register 41, second buffercircuits 42A and 42B and the power supply circuit 43 shown in FIG. 7 isincluded in vertical circuit V1. The other elements are included invertical circuit V2. Each second circuit unit 40 may be divided in anarbitrary way, and various forms can be applied depending on thestructure of the second circuit units 40. Each second circuit unit 40may be divided into three or more vertical circuits.

In the example of FIG. 9, horizontal circuits H1 and H2 are arranged inthe second direction Y in a manner similar to that of FIG. 8. However,horizontal circuits H1 and H2 are out of alignment in the firstdirection X. Specifically, horizontal circuits H1 shift to the left (ina direction away from the display area DA) in comparison with respectivehorizontal circuits H2 in the figure. When two circuits are out ofalignment in the first direction X, for example, the line segmentconnecting the center of one of the two circuits in the first directionX and the center of the other one in the first direction X is notparallel to the second direction Y.

When horizontal circuits H1 and H2 are out of alignment in the abovemanner, the layout of the peripheral area SA can be further improved interms of efficiency. In the example of FIG. 8, a space like an area 50may be defined around each first circuit unit 30. However, in theexample of FIG. 9, such an area can be effectively used to arrange eachfirst circuit unit 30.

Vertical circuits V1 and V2 are arranged in the first direction X.Vertical circuits V1 and V2 are out of alignment in the second directionY. Specifically, vertical circuits V1 shift to the lower side incomparison with respective vertical circuits V2 in the figure. When twocircuits are out of alignment in the second direction Y, for example,the line segment connecting the center of one of the two circuits in thesecond direction Y and the center of the other one in the seconddirection Y is not parallel to the first direction X.

Now, this specification explains the circuit layout in the second areaA2. FIG. 10 shows an example of a circuit layout applicable to thesecond driver unit 4 in the second area A2. This second driver unit 4corresponds to the second driver unit 4 shown in FIG. 8. Thus, eachsecond circuit unit 40 is not divided into a plurality of verticalcircuits. However, each second circuit unit 40 may be divided into aplurality of vertical circuits in a manner similar to that of FIG. 9.For example, even when each second circuit unit 40 is divided intovertical circuits V1 and V2 in the first area A1 as shown in FIG. 9,each second circuit unit 40 may not be divided in the second area A2.

In the second area A2, no first driver unit 3 is provided between thesecond driver unit 4 and the display area DA. Thus, the second driverunit 4 is allowed to be close to the display area DA in comparison withFIG. 1 and FIG. 10. For example, when the distance between the secondcircuit units 40 and the display area DA in the first area A1 is a firstdistance, and the distance between the second circuit units 40 and thedisplay area DA in the second area A2 is a second distance, the seconddistance can be less than the first distance.

Now, this specification explains a specific example of a circuit layoutapplicable to the first area A1 with reference to FIG. 11. FIG. 11 showssome of the subpixels SP arranged in the display area DA in addition tothe first area A1 (peripheral area SA).

FIG. 11 shows four first circuit units 30 and three second circuit units40. A first line WL1 supplied with the first drive signal xFRP and asecond line WL2 supplied with the second drive signal FRP extend betweenthe first circuit units 30 and the display area DA. For example, thefirst drive line DL1 shown in FIG. 3 is connected to the first line WL1.For example, the second drive line DL2 shown in FIG. 3 is connected tothe second line WL2. In the example of FIG. 11, a third line WL3 towhich voltage VSS is applied and a fourth line WL4 to which voltage VDD1is applied further extend between the first circuit units 30 and thedisplay area DA. Voltages VSS and VDD1 of the third and fourth lines WL3and WL4 are also applied to the subpixels SP and are used to drive thememories 10. The first to fourth lines WL1 to WL4 are bent along thedisplay area DA. In FIG. 11, the first to fourth lines WL1 to WL4 arebent in a stepwise manner. The number of corresponding first circuitunits 30 differs depending on the stage. Specifically, the number offirst circuit units 30 corresponding to the central stage (first stage)of the first to fourth lines WL1 to WL4 in FIG. 11 is two (HU1 and HU2).The number of first circuit units 30 corresponding to the stages (secondstages) adjacent to the central stage is one. Since the number ofcorresponding first circuit units 30 differs depending on the stage, thespace can be efficiently used. The number of first circuit units 30adjacent to each other in the first stage is not limited to two, and maybe another number. The number of first circuit units 30 in each secondstage is not limited to one, and may be another number.

For example, a guard ring 60 supplied with a common signal VCOM isprovided in the peripheral area SA in a circular pattern along the outercircumferential edge of the peripheral area SA. The guard ring 60functions to prevent the static electricity, etc., supplied from outsidefrom having an influence on each circuit of the peripheral area SA. Thefirst and second circuit units 30 and 40 are provided between the guardring 60 and the display area DA.

Dummy pixels DSP are arranged along the outline of the display area DAbetween the first line WL1 and the display area DA. For example, in aplanar view, the dummy pixels DSP have the same shape as the subpixelsSP, and are arranged at the same pitch as the subpixels SP. For example,each dummy pixel DSP comprises the pixel electrode PE and the gatecircuit 11; however, at least, each dummy pixel DSP does not comprisethe memory 10. The second drive signal FRP which is a non-display signalis always supplied to the pixel electrode PE of each dummy pixel DSP.Thus, black display is always applied to each dummy pixel DSP. Eachdummy pixel DSP is a pixel which does not display an image.

The number of columns of pixels (signal lines) driven by each firstcircuit unit 30 is two or more, and is six in FIG. 11. The number ofdummy pixels DSP connected to each signal line S differs in the sixsignal lines S. When the adjacent first circuit units 30 are comparedwith each other, the mean number of dummy pixels DSP connected to eachsignal line S differs. Specifically, in FIG. 11, the mean number ofdummy pixels DSP connected to each signal line S corresponding to HU1equivalent to the first circuit unit 30 in the first area A1 is 1.6 (8/5). The mean number of dummy pixels DSP connected to each signal lineS corresponding to HU2 equivalent to the first circuit unit 30 in thefirst area A1 is 0.6 (⅗). In the entire edge of the display area DA, thedummy pixels DSP are randomly arranged, and fill the space between thefirst line WL1 and the display area DA.

FIG. 12 is an enlarged view of the first circuit unit 30 of FIG. 11.FIG. 13 is an enlarged view of the second circuit unit 40 of FIG. 11.The first circuit unit 30 of FIG. 12 comprises horizontal circuits H1,H2 and H3 (first to third circuits, respectively). Horizontal circuit H1includes the first shift register 31. Horizontal circuit H2 includes thefirst latch circuit 32. Horizontal circuit H3 includes the second latchcircuit 33 and the first buffer circuit 34. Horizontal circuits H1 andH2 are connected via the above first connective lines CL1. Horizontalcircuits H2 and H3 are connected via the above second connective linesCL2. In horizontal circuit H3, the second latch circuit 33 is connectedto the first buffer circuit 34 via the above third connective lines CL3.

Lines which apply voltages VSS and VDD1 and supply clock HCK and a resetsignal xRST to the first shift register 31 are connected to horizontalcircuit H1. A line which applies voltages VSS and VDD1 to the firstlatch circuit 32 is connected to horizontal circuit H2. Lines whichapply voltages VSS and VDD1 and timing pulses Ds and xDs to the secondlatch circuit 33 and the first buffer circuit 34 are connected tohorizontal circuit H3. In FIG. 11 and FIG. 12, to simplify the figures,a plurality of lines connected to horizontal circuits H1 to H3 arearbitrarily shown by a single line segment.

The second circuit unit 40 of FIG. 13 comprises vertical circuits V1 andV2 (fourth and fifth circuits, respectively). Vertical circuit V1includes the second shift register 41. Vertical circuit V2 includessecond buffer circuits 42A and 42B and the power supply circuit 43.Vertical circuits V1 and V2 are connected via the above fourthconnective line CL4. Second buffer circuits 42A and 42B are connected torespective scanning lines GD. The power supply circuit 43 is connectedto the first power line LP1 which applies power source voltage VRAM.

Lines which apply voltages VSS and VDD2 and supply clock VCK and a resetsignal xRST to the second shift register 41 are connected to verticalcircuit V1. Lines which apply voltages VSS, VDD1 and VDD2 and supplyenable signals ENB1 and ENB2 to second buffer circuits 42A and 42B andthe power supply circuit 43 are connected to vertical circuit V2. InFIG. 11 and FIG. 13, to simplify the figures, a plurality of linesconnected to vertical circuits V1 and V2 are arbitrarily shown by asingle line segment.

As shown in FIG. 12, the two scanning lines GD (first scanning lines)and the first power line LP1 connected to a second circuit unit 40extend in the first direction X between horizontal circuits H1 and H2.The two scanning lines GD (second scanning lines) and the first powerline LP1 connected to another second circuit unit 40 extend in the firstdirection X between horizontal circuits H2 and H3. Further, the twoscanning lines GD and the first power line LP1 connected to anothersecond circuit unit 40 extend in the first direction X betweenhorizontal circuit H3 and the fourth line WL4. The data buses DBL extendin the first direction X between horizontal circuits H1 and H2.

In a planar view, the scanning lines GD, the first power line LP1 andthe data buses DBL between horizontal circuits H1 and H2 intersect withthe first connective lines CL1. In a planar view, the scanning lines GDand the first power line LP1 between horizontal circuits H2 and H3intersect with the second connective lines CL2.

In the example of FIG. 12, the signal lines S are connected to the firstbuffer circuit 34 via lead lines Sa connected to the first buffercircuit 34. The scanning lines GD and the first power line LP1 betweenhorizontal circuit H3 and the fourth line WL4 intersect with the leadlines Sa in a planar view. Further, the first to fourth lines WL1 to WL4intersect with the lead lines Sa in a planar view.

Horizontal circuits H1 to H3 are arranged in the second direction Y.Horizontal circuits H1 to H3 are out of alignment in the first directionX. Specifically, horizontal circuit H2 shifts to the left in comparisonwith horizontal circuit H3 in the figure. Horizontal circuit H1 furthershifts to the left in comparison with horizontal circuit H2. The linesare bent from the first direction X to the second direction Y in areasgenerated by shifting horizontal circuits H1 to H3 in the above manner.

In the example of FIG. 12, the signal lines S are out of alignment withrespect to horizontal circuit H3 (the first buffer circuit 34) in thefirst direction X. The lead lines Sa extend such that they are inclinedin a direction intersecting with both the first direction X and thesecond direction Y. Since the signal lines S are out of alignment withrespect to horizontal circuit H3, the circuit layout of the peripheralarea SA can be more freely designed. The first circuit unit 30 does nothave to be provided on the extended lines of the signal lines S as theconnection destination. In the example of FIG. 12, the second connectivelines CL2 also extend such that they are inclined in a directionintersecting with both the first direction X and the second direction Y.When lines are inclined in a manner similar to that of the lead lines Saand the second connective lines CL2, the lines can be shorter than whenthey are bent in the first and second directions X and Y. In thismanner, the space of the peripheral area SA can be more effectivelyused.

In the example of FIG. 13, vertical circuits V1 and V2 are arranged inthe first direction X, and are out of alignment in the second directionY. In areas generated by shifting vertical circuits V1 and V2 in thismanner, the lines are bent from the first direction X to the seconddirection Y.

For example, each line shown in FIG. 11 to FIG. 13 is formed of a metalmaterial or a conductive material such as ITO in first and second layersof the first substrate SUB1. An insulating layer is provided between thefirst layer and the second layer. One of two lines intersecting witheach other in FIG. 11 to FIG. 13 is formed in the first layer. The otherone is formed in the second layer. Thus, these lines are notelectrically connected to each other.

For example, the scanning lines GD and the first power lines LP1 areformed in the first layer. The other lines such as the signal lines S,the first to fourth lines WL1 to WL4 and the data buses DBL are formedin the second layer. For example, the first connective lines CL1 need toavoid the scanning lines GD and the first power line LP1 formed in thefirst layer and the data buses DBL formed in the second layer. In thiscase, of the first connective lines CL1, the portion intersecting withthe scanning lines GD and the first power line LP1 may be formed in thesecond layer. The portion intersecting with the data buses DBL may beformed in the first layer. These two portions may be connected to eachother via a contact hole provided in the insulating layer.

The first substrate SUB1 is not limited to a structure having two layersincluding the first and second layers. The first substrate SUB1 may havemore layers such that the lines are dispersed into the layers.

Each lead line Sa comprises a first portion Sa1 intersecting with thescanning lines GD and the first power line LP1 between horizontalcircuit H3 and the fourth line WL4, and a second portion Sa2intersecting with the first to fourth lines WL1 to WL4. The firstportion Sa1 extends from horizontal circuit H3 to the contact positionbetween the scanning lines GD and the fourth line WL4. The secondportion Sa2 extends from the above contact position to the signal lineS. The first portion Sa1 is formed in the second layer to avoid thescanning lines GD and the first power line LP1 formed in the firstlayer. The second portion Sa2 is formed in the first layer to avoid thefirst to fourth lines WL1 to WL4 formed in the second layer. The firstportion Sa1 is connected to the second portion Sa2 at the contactposition.

As is clear from FIG. 12, if the lead lines Sa extend in the seconddirection Y, and are connected to the signal lines S on the extendedlines of the lead lines Sa, the lead lines Sa pass through the area inwhich the scanning lines GD and the first power line LP1 intersect withthe first to fourth lines WL1 to WL4. The scanning lines GD and thefirst power line LP1 are formed in a layer different from that of thefirst to fourth lines WL1 to WL4 to avoid electrical contact. Thus, anew layer for forming the lead lines Sa is required to cause the leadlines Sa to pass through the area. However, when the lead lines Sa areinclined so as to avoid the area in which the scanning lines GD and thefirst power line LP1 intersect with the first to fourth lines WL1 to WL4as shown in FIG. 12, there is no need to provide a new layer.

In the embodiment explained above, at least a part of the first driverunit 3 is provided between the second driver unit 4 and the display areaDA. In this way, it is possible to prevent a useless space in theperipheral area SA, and reduce the width of the frame.

Further, each first circuit unit 30 is divided into a plurality ofhorizontal circuits such that the scanning lines GD and the data busesDEL pass between the horizontal circuits. In this way, the circuitlayout of the peripheral area SA can be improved in terms of efficiency.

In addition, the horizontal circuits are out of alignment. Thus, thecircuit layout of the peripheral area SA can be further improved interms of efficiency. When each second circuit unit 40 is divided into aplurality of vertical circuits, and the vertical circuits are out ofalignment, a similar effect can be obtained.

Apart, from this effect, various effects can be obtained from thepresent embodiment as described earlier.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

For example, in the above embodiment, the display device in digital modeis disclosed. However, the circuit layout of the peripheral area SA inthe above embodiment may be applied to a display device in analog modein which an analog video signal is supplied to each pixel electrode PEvia signal lines S to obtain a multilevel display image. Further, thecircuit layout of the peripheral area SA in the above embodiment, may beapplied to a display device having both the function of digital mode andthe function of analog mode.

The structures of the first and second circuit units 30 and 40 disclosedin FIG. 6 and FIG. 7 and the circuit layout of the peripheral area SAdisclosed in FIG. 11 to FIG. 13 are merely examples. Some of the circuitelements or lines shown in the drawings may be appropriately removed. Anew circuit element or line may be added.

What is claimed is:
 1. A display device comprising: a pair of substrates comprising a display area in which a plurality of pixels are arranged; an optical element layer provided between the pair of substrates; pixel electrodes provided in the respective pixels; signal lines supplied with video signals to the respective pixels; switching elements connecting the signal lines; scanning lines supplied with scanning signals for controlling the switching elements; a first driver unit which is provided in a peripheral area around the display area and is configured to supply the video signals to the signal lines; and a second driver unit provided in the peripheral area and configured to supply the scanning signals to the scanning lines, wherein at least a part of the first driver unit is provided between the display area and the second driver unit, the first driver unit comprises a plurality of first circuit units, the second driver unit comprises a plurality of second circuit units, the peripheral area comprises a first area in which at least one of the first circuit units and at least one of the second circuit units are formed, and a second area in which at least one of the second circuit units are formed and the first circuit units are not formed, a distance between the second circuit unit and the display area in the first area is a first distance, a distance between the second circuit unit and the display area in the second area is a second distance, the second distance is less than the first distance, at least one of the pair of substrates has a first arc-edge in a part of an outline, the first area is an area between the first arc-edge and the display area, one of the first circuit units includes a first circuit and a second circuit in the first area, the second circuit is connected to one of the signal lines, the first circuit is connected to the second circuit by a first conductive line, and is not directly connected to the one of the signal lines, one of the second circuit units is connected to one of the scanning lines in the first area, and the one of the scanning lines crosses the first conductive line in the first area.
 2. The display device of claim 1, wherein the one of the pair of substrates has a second arc-edge in a part of the outline, and the second area is an area between the second arc-edge and the display area.
 3. The display device of claim 2, wherein a distance between the first arc-edge and the display area in the first area is a third distance, a distance between the second arc-edge and the display area in the second area is a fourth distance, and the third distance is same as the fourth distance.
 4. The display device of claim 2, wherein the second driver unit includes a first part, a second part, and a third part, the first part is formed along the first arc-edge in the first area, the second part is formed along the second arc-edge in the second area, the third part is between the first part and the second part, and the third part is formed in a straight line between the first area and the second area.
 5. The display device of claim 1, wherein the signal lines are arrayed in a first direction in the display area, the scanning lines are arrayed in a second direction in the display area, the second direction is a direction which intersects the first direction, and the first circuit is shifted obliquely from the second circuit with respect to the first direction and the second direction in the first area.
 6. The display device of claim 5, wherein one of the second circuit units includes a third circuit and a fourth circuit in the first area, the fourth circuit is connected to one of the scanning lines, the third circuit is connected to the fourth circuit by a second conductive line, and is not directly connected to the one of the scanning lines, the third circuit is shifted obliquely from the fourth circuit with respect to the first direction and the second direction in the first area.
 7. A display device comprising: a pair of substrates comprising a display area in which a plurality of pixels are arranged; an optical element layer provided between the pair of substrates; pixel electrodes provided in the respective pixels; signal lines supplied with video signals to the respective pixels; switching elements connecting the signal lines; scanning lines supplied with scanning signals for controlling the switching elements; a first driver unit which is provided in a peripheral area around the display area and is configured to supply the video signals to the signal lines; and a second driver unit provided in the peripheral area and configured to supply the scanning signals to the scanning lines, wherein at least a part of the first driver unit is provided between the display area and the second driver unit, the first driver unit comprises a plurality of first circuit units, the second driver unit comprises a plurality of second circuit units, the peripheral area comprises a first area in which at least one of the first circuit units and at least one of the second circuit units are formed, and a second area in which at least one of the second circuit units are formed and the first circuit units are not formed, a distance between the second circuit unit and the display area in the first area is a first distance, a distance between the second circuit unit and the display area in the second area is a second distance, the second distance is less than the first distance, at least one of the pair of substrates has a first arc-edge in a part of an outline, the first area is an area between the first arc-edge and the display area, one of the second circuit units includes a third circuit and a fourth circuit in the first area, the fourth circuit is connected to one of the scanning lines, the third circuit is connected to the fourth circuit by a second conductive line, and is not directly connected to the one of the scanning lines, the signal lines are arrayed in a first direction in the display area, the scanning lines are arrayed in a second direction in the display area, the second direction is a direction which intersects the first direction, and the third circuit is shifted obliquely from the fourth circuit with respect to the first direction and the second direction in the first area. 